直流备用电源是变电站安全稳定运行的重要保证,厂站中目前常用的铅酸蓄电池存在着寿命低、温度性能差的问题。锂离子电池的长循环寿命、高能量密度等特点,近年随着技术不断成熟,有望成为替代方案。电池健康状态(state of health,SOH)是...直流备用电源是变电站安全稳定运行的重要保证,厂站中目前常用的铅酸蓄电池存在着寿命低、温度性能差的问题。锂离子电池的长循环寿命、高能量密度等特点,近年随着技术不断成熟,有望成为替代方案。电池健康状态(state of health,SOH)是锂离子电池储能系统可靠运行所需的核心参数,而电化学阻抗谱(electrochemical impedance spectroscopy,EIS)作为一种无损检测的方法,可用来评估电池的SOH并分析其老化的主要机制。针对静态EIS在电池工作情况下获取困难、带直流偏置的快速EIS可解释性不足的问题,本研究提出了一种基于快速阻抗谱可解释性增强的锂离子电池健康状态估计方法,在基本不影响直流电源工作的情况下快速完成电池老化预测与老化机制分析。首先,利用卷积-长短期记忆网络模型实现了动态到静态的EIS预测,卷积网络提取关键特征,长短期记忆神经网络捕捉序列间依赖关系,以实现电池老化机理解析;其次,提出了一种基于极限梯度提升算法及EIS的电池SOH估计方法,捕捉静态EIS与SOH之间的高度非线性映射关系,完成了电池SOH的在线评估,并依靠特征分裂增益量化不同频域特征的贡献以分析EIS的不同形式在预测结果中的重要性。实验表明,所提静态EIS预测方法的平均绝对误差(mean absolute error,MAE)为1.75×10-5;电池SOH估计结果的MAE仅为2.43%,电解液损失是所用电池老化的主要原因。展开更多
The graded bandgap of kesterite based absorber layer is an important way to achieve high efficiency solar cells. Incorporation of Ag into CZTSSe thin films can adjust the bandgap and thus reduce the VOC-deficit and im...The graded bandgap of kesterite based absorber layer is an important way to achieve high efficiency solar cells. Incorporation of Ag into CZTSSe thin films can adjust the bandgap and thus reduce the VOC-deficit and improve the quality of crystallization. However, the distribution of Ag is difficult to control due to the quick diffusion of Ag under the high temperature. In this study, we achieve the front Ag-gradient in kesterite structured compound films by prealloying followed by selenization process at 550 °C. AgZn3,Ag3Sn, and Sn–Ag–Cu alloy phases were formed during prealloying stage at 250 °C. After prealloying process, Ag tends to distribute at the front surface of the ACZTSe thin films. Combining the results of experiment and SCAPS simulation, the significantly VOCimprovement of devices is ascribed to the formation of the front Ag-gradient bandgap structure in the absorber layer. This facile prealloying selenization process affords a feasible method to design the graded bandgap structure absorber layers, which will promote the fabrication of high efficient graded bandgap structure solar cells.展开更多
基金supported by the National Natural Science Foundation of China(51572132,61674082,61774089)Tianjin Natural Science Foundation of Key Project(16JCZDJC30700,18JCZDJC31200)+1 种基金YangFan Innovative and Entrepreneurial Research Team Project(2014YT02N037)111 Project(B16027)
文摘The graded bandgap of kesterite based absorber layer is an important way to achieve high efficiency solar cells. Incorporation of Ag into CZTSSe thin films can adjust the bandgap and thus reduce the VOC-deficit and improve the quality of crystallization. However, the distribution of Ag is difficult to control due to the quick diffusion of Ag under the high temperature. In this study, we achieve the front Ag-gradient in kesterite structured compound films by prealloying followed by selenization process at 550 °C. AgZn3,Ag3Sn, and Sn–Ag–Cu alloy phases were formed during prealloying stage at 250 °C. After prealloying process, Ag tends to distribute at the front surface of the ACZTSe thin films. Combining the results of experiment and SCAPS simulation, the significantly VOCimprovement of devices is ascribed to the formation of the front Ag-gradient bandgap structure in the absorber layer. This facile prealloying selenization process affords a feasible method to design the graded bandgap structure absorber layers, which will promote the fabrication of high efficient graded bandgap structure solar cells.
